The present invention relates to the field of undersea diving, and in particular to the field of decompression buoys used during undersea diving.
A decompression buoy is equipment used in undersea diving during a decompression stop. It serves to provide a mark at the surface showing the position of the diver at the end of a dive, and that a diver is returning to the surface with safety stops. The decompression buoy also enables a diver to stay in position at a constant depth in open water so as to facilitate the stop.
Conventionally, a decompression buoy comprises an inflatable bag of generally cylindrical shape and a retaining line connecting the bag when inflated to the diver whose presence it serves to indicate. The decompression buoy is designed to float vertically at the surface of the water and it is of bright color (orange or yellow) so as to be visible to third parties present at the surface of the water.
In order to facilitate inflation of the decompression buoy underwater by the diver, the decompression buoy conventionally includes a large opening at its base. The large opening makes it easier for the diver to put the diving regulator into the opening in order to inflate the decompression buoy.
Nevertheless, when the decompression buoy is in use and floating at the surface of the water in the inflated state, it can sag or lie down on the surface of the water. This happens in particular when the tension exerted by the diver on the retaining means is insufficient or when the decompression buoy on the surface is subjected to a large amount of swell or to a strong wind. Under such circumstances, the large opening can lead to the decompression buoy deflating, thus making it inoperative.
In order to solve such a problem, it is known to fit a decompression buoy with a check valve that is positioned in the proximity of the large opening: the check valve prevents the decompression buoy from deflating. Nevertheless, it is also necessary to provide a pressure release valve to prevent the buoy exploding as it rises to the surface, thereby increasing the cost of fabrication and the overall size of the decompression buoy. Finally, deflating the decompression buoy is also made more complicated by the presence of the check valve.
There thus exist decompression buoys, e.g. the Mares surface marker buoy (SMB), that are cylindrical in shape with ballast means at the opening. Such buoys are geometrically shaped so that inflating the buoy into shape leads to the opening becoming pinched, thereby closing the buoy to an extent that is proportional to the pressure inside the buoy: this produces a check valve effect that prevents air from escaping through the opening. A pressure release valve is then necessary firstly in order to avoid the buoy exploding while it is rising and secondly to enable the buoy to be deflated so that it can be stored.